Since i am a newbie,i have a problem regarding joining two common ground on the board.In this case the first led is connected to ground and some pin no. but the 2nd and third led,their anodes are connected to the pin nos. on the arduino board but their cathode is just left on the ground rail on the breadboard.What i am confused is can we connect these two ground from 2nd and 3rd led with the 1st led?